JPH11337827A - Optical system and image pickup device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the whole length of an image pickup device by providing an optical element in which a curved reflection surface tilted with respect to a standard axis is an aspherical surface in which two pieces or more of symmetrical surfaces deciding a pair of the symmetric surfaces don't exist and providing an incident pupil on the objective side of the curved reflection surface. SOLUTION: The optical system is provided with the optical element provided with the curved reflection surface tilted with respect to the standard axis and in which the curved surface reflection surface is an aspherical surface in which two pieces or more of symmetrical surfaces deciding a pair of the symmetric surfaces don't exist and the incident pupil is provided on the objective side of the curved surface reflection surface of the optical element. A first optical element B1 consists of a concave diffraction surface R1.1 , the reflection surfaces of a concave mirror R1.2 , a convex mirror R1.3 , a convex mirror R1.4 , a convex mirror R1.5 and a convex diffraction surface R1.6 in order from the objective side and the direction of the incident standard axis is in parallel to an the same as the direction of the outgoing standard axis. A second optical element B2 consists of a convex diffraction surface R2.1 , the reflection surfaces of a convex mirror R2.2 , a concave mirror R2.3 , a convex mirror R2.4 , a concave mirror R2.5 and a convex diffraction surface R2.6 from the objective side an the direction of the incident standard axis is in parallel to and the same as the direction of the outgoing standard axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system and an imaging apparatus using the same, and is suitable for a video camera, a still video camera, a copying machine, and the like.

[0002]

2. Description of the Related Art Conventionally, various photographing optical systems using a reflecting surface such as a concave mirror or a convex mirror have been proposed. FIG.
FIG. 2 is a schematic diagram of a so-called mirror optical system including one concave mirror and one convex mirror.

In the mirror optical system shown in FIG. 1, an object light beam 104 from an object is reflected by a concave mirror 101, converges toward the object side, is reflected by a convex mirror 102, and is reflected by an image plane.
Image at 103.

This mirror optical system is based on a so-called Cassegrain-type reflection telescope, and the optical path of a long-lens telephoto lens system composed of a refractive lens is folded by using two opposing reflection mirrors. The purpose is to shorten the entire length of the optical system.

[0005] For the same reason, in the objective lens system constituting the telescope, for the same reason, in addition to the Cassegrain type, there are known many types in which the entire length of the optical system is shortened by using a plurality of reflecting mirrors.

As described above, a compact mirror optical system is obtained by efficiently folding the optical path by using a reflecting mirror instead of a lens of a photographic lens having a longer overall lens length than before.

However, a mirror optical system such as a Cassegrain type reflection telescope generally has a problem that a part of the object beam is vignetted by the convex mirror 102. This problem is caused by the presence of the convex mirror 102 in the area where the object light beam 104 passes.

In order to solve this problem, the reflecting mirror is used eccentrically so as to prevent the passing area of the object light beam 104 from being blocked by other parts of the optical system, ie, the principal ray of the light beam.
A mirror optical system that separates 106 from the optical axis 105 has also been proposed.

FIG. 60 is a schematic diagram of a mirror optical system disclosed in US Pat. No. 3,674,334, in which a part of a reflecting mirror rotationally symmetric with respect to the optical axis is used to generate a main beam of an object light beam. The problem of vignetting is solved by separating the light beam from the optical axis.

The mirror optical system shown in FIG. 1 includes a concave mirror 111, a convex mirror 113, and a concave mirror 112 in the order in which light beams pass, and they originally have an optical axis 114 as shown by two-dot broken lines in the figure.
This is a reflection mirror rotationally symmetric with respect to. Concave mirror
111 is used only on the upper side of the paper with respect to the optical axis 114, the convex mirror 113 is used only on the lower side of the paper with respect to the optical axis 114, and the concave mirror 112 is used only on the lower side of the paper with respect to the optical axis 114.
Is separated from the optical axis 114 to constitute an optical system in which vignetting of the object light beam 115 is eliminated.

FIG. 61 is a schematic view of a mirror optical system disclosed in US Pat. No. 5,063,586. The mirror optical system shown in the figure solves the above problem by decentering the central axis of the reflection mirror itself with respect to the optical axis and separating the principal ray of the object light beam from the optical axis.

In FIG. 1, when the vertical axis of the object plane 121 is defined as an optical axis 127, the center coordinates and the center axis of the respective reflecting surfaces of the convex mirror 122, concave mirror 123, convex mirror 124, and concave mirror 125 in the order of passage of the light flux The axes 122a, 123a, 124a and 125a connecting the center of the reflecting surface and the center of curvature of the surface are eccentric with respect to the optical axis 127. In this figure, by appropriately setting the amount of eccentricity and the radius of curvature of each surface at this time, vignetting of the object light beam 128 by each reflection mirror is prevented, and the object image is efficiently formed on the image forming surface 126. I have.

In addition, US Pat. No. 4,737,021 and US Pat. No. 4,265,510 also disclose a configuration in which a part of a reflection mirror rotationally symmetric with respect to the optical axis is used to avoid vignetting, or the central axis of the reflection mirror is used as a light source. A configuration is disclosed in which the shaft is eccentric with respect to the shaft to avoid vignetting.

There is also known a zooming technique for changing the imaging magnification (focal length) of the photographing optical system by relatively moving a plurality of reflecting surfaces constituting the mirror optical system.

For example, in the specification of US Pat. No. 4,812,030, in the configuration of the Cassegrain type reflecting telescope shown in FIG. 59, the distance between the concave mirror 101 and the convex mirror 102 and the convex mirror 10
A technique for changing the magnification of the photographing optical system by relatively changing the interval from 2 to the image plane 103 is disclosed.

FIG. 62 shows another embodiment disclosed in the publication. In the figure, an object light beam 138 from an object is incident on a first concave mirror 131 and is reflected on this surface to become a convergent light beam and is incident on a first convex mirror 132 toward the object side, where it is reflected on the image forming surface side. It becomes a substantially parallel light beam and the second convex mirror 134
And is reflected by this surface to become a divergent light beam, and is incident on the second concave mirror 135, where it is reflected to become a convergent light beam and forms an image on the image plane 137.

In this configuration, the distance between the first concave mirror 131 and the first convex mirror 132 is changed, and
Zooming is performed by changing the distance between the fourth concave mirror 135 and the second concave mirror 135 to change the focal length of the entire mirror optical system.

In the specification of US Pat. No. 4,993,818, an image formed by a Cassegrain-type reflection telescope shown in FIG. 59 is secondarily formed by another mirror optical system provided at a subsequent stage, and this secondary image is formed. The magnification of the entire photographing system is changed by changing the imaging magnification of the image mirror optical system.

These reflection type photographing optical systems have a large number of components, and it is necessary to assemble each optical component with high accuracy in order to obtain necessary optical performance. In particular, since the relative position accuracy of the reflection mirrors is severe, it is necessary to adjust the positions and angles of the reflection mirrors.

As one method for solving this problem, a method has been proposed in which, for example, a mirror system is divided into a single block to avoid errors in assembling optical components during assembly.

Conventionally, as an example in which a large number of reflecting surfaces are formed into one block, there are optical prisms such as a pentagonal roof prism and a Porro prism used for a finder system or the like.

In these prisms, since a plurality of reflecting surfaces are integrally formed, the relative positional relationship between the respective reflecting surfaces is made with high precision, and it is not necessary to adjust the positions of the reflecting surfaces. However, the main function of these prisms is to reverse the image by changing the traveling direction of the light beam, and each reflecting surface is formed of a plane.

On the other hand, there is also known an optical system in which a reflecting surface of a prism has a curvature.

FIG. 63 is a schematic view of a main part of an observation optical system disclosed in US Pat. No. 4,775,217. This observation optical system is an optical system for observing an external scenery and observing a display image displayed on an information display body while overlapping the scenery.

In this observation optical system, the display light flux 145 emitted from the display image of the information display body 141 is reflected by the surface 142, goes to the object side, and enters the concave half mirror surface 143. After being reflected by the half mirror surface 143, the display light beam 145 becomes a substantially parallel light beam due to the refracting power of the concave surface 143. After refraction and transmission through the surface 142, an enlarged virtual image of the display image is formed and the observer's image is formed. The light enters the pupil 144 to make the viewer recognize the displayed image.

On the other hand, the object light beam 146 from the object is
The light enters a surface 147 substantially parallel to 2 and is refracted to reach a concave half mirror surface 143. A semi-transmissive film is deposited on the concave surface 143, and a part of the object light beam 146 transmits through the concave surface 143 and
After being refracted and transmitted through 2, the light enters the pupil 144 of the observer. Thus, the observer visually recognizes the display image in the outside scenery while overlapping.

FIG. 64 is a schematic view of a main part of an observation optical system disclosed in Japanese Patent Application Laid-Open No. 2-279516. This observation optical system is also an optical system for observing an external scenery and observing a display image displayed on an information display body in an overlapping manner.

In this observation optical system, the display light beam 154 emitted from the information display body 150 is applied to the flat surface 15 constituting the prism Pa.
7 and enters the prism Pa and enters the parabolic reflecting surface 151. The display light beam 154 is reflected by the reflection surface 151 to become a convergent light beam and forms an image on the focal plane 156. At this time, the reflective surface 151
The display light beam 154 reflected by the light source 2 forms the prism Pa
The light reaches the focal plane 156 while being totally reflected between the two parallel planes 157 and 158, thereby achieving a reduction in the thickness of the entire optical system.

Next, the display light beam 154 emitted as divergent light from the focal plane 156 is incident on a parabolic half mirror 152 while being totally reflected between the planes 157 and 158, and is reflected by the half mirror surface 152. Simultaneously, the refracting power forms an enlarged virtual image of the display image and forms a substantially parallel light flux, which passes through the surface 157 and enters the observer's pupil 153,
This allows the viewer to recognize the display image.

On the other hand, the object light beam 155 from the outside
The light passes through a surface 158b constituting Pb, passes through a parabolic half mirror 152, passes through a surface 157, and enters the pupil 153 of the observer. The observer visually recognizes the displayed image in an overlapping manner in the outside scenery.

Further, as examples of using an optical element on the reflecting surface of a prism, for example, Japanese Patent Application Laid-Open Nos.
There is an optical head for an optical pickup disclosed in Japanese Patent No. 139612 or the like. These devices reflect light from a semiconductor laser on a Fresnel surface or a hologram surface, form an image on a disk surface, and guide reflected light from the disk to a detector.

[0032]

The above U.S. Pat. No. 3,674,33
No. 4, U.S. Pat.No. 5,063,586, U.S. Pat.
In each of the mirror optical systems having the eccentric mirror disclosed in the specification of Japanese Patent No. 265,510, each reflecting mirror is arranged with a different amount of eccentricity, so that the mounting structure of each reflecting mirror becomes very complicated and the mounting accuracy is reduced. It is very difficult to secure.

Further, the photographing optical systems having a zooming function disclosed in US Pat. No. 4,812,030 and US Pat. No. 4,993,818 each have a large number of constituent parts such as a reflecting mirror and an image forming lens, and thus are necessary. In order to obtain high optical performance,
It was necessary to assemble each optical component with high accuracy.

In particular, since the relative position accuracy of the reflection mirrors becomes severe, it is necessary to adjust the position and angle of each reflection mirror.

The conventional reflection type photographing optical system has a configuration suitable for a so-called telephoto type lens system having a long overall optical system and a small angle of view. In addition, when obtaining a photographing optical system that requires an angle of view of a standard lens to an angle of view of a wide-angle lens, the number of reflecting surfaces required for aberration correction increases, so higher component accuracy and higher assembly accuracy are required. And the cost or the whole tends to be large.

Further, the observation optical systems disclosed in the above-mentioned US Pat. No. 4,775,217 and Japanese Patent Application Laid-Open No. 2-279516 are all displayed on an information display which is arranged away from the pupil of the observer. Focusing on pupil imaging and changing the direction of travel of light to efficiently transmit the displayed image to the observer's pupil, and a technology for actively correcting aberrations with a reflective surface with curvature Is not disclosed directly.

Further, Japanese Patent Application Laid-Open Nos. 5-12704 and 6-1396
The optical systems for optical pickups disclosed in Japanese Patent Publication No. 12 and the like are all limited to the use of a detection optical system, and are not applicable to an imaging optical system, particularly to an imaging apparatus using an area-type imaging device such as a CCD. The image performance was not satisfactory.

According to the present invention, an optical system capable of reducing the size of the entire mirror optical system and reducing the disposition accuracy (assembly accuracy) of the reflection mirror, which is common in the mirror optical system, and an image pickup apparatus using the same The purpose is to provide.

[0039] Further, by arranging the stop closest to the object side and forming an object image at least once in the optical system, the effective diameter of the optical system can be reduced.
By giving appropriate refractive power to the plurality of reflecting surfaces constituting the optical element and eccentrically arranging the reflecting surfaces constituting each optical element, the optical path is bent into a desired shape and the total length in a predetermined direction is reduced. And an image pickup apparatus using the same.

[0040]

An optical system according to the present invention has a curved reflecting surface inclined with respect to a reference axis, and the curved reflecting surface defines a pair of symmetric surfaces. There is provided an aspherical optical element having no more than one optical element, and an entrance pupil is provided on the object side of the curved reflecting surface of the optical element.

The optical system according to the second aspect of the present invention has a curved reflecting surface inclined with respect to the reference axis, and the curved reflecting surface is an aspherical surface having only one symmetric surface defining a pair of symmetric surfaces. An optical element is provided, and an entrance pupil is provided on the object side of the optical element.

The optical system according to the third aspect of the present invention has a curved reflecting surface inclined with respect to the reference axis, and the curved reflecting surface is A = (a + b) · (y ² · cos ² t + x ² ) B = 2a ・ b ・ cos t [1 + {(ba) ・ y ・ sin t / (2a ・ b)} + [1 + {(ba)
・ Y ・ sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin
² t} x ² / (4a ² b ² cos ² t)) ^1/2 ] as z = A / B + C ₀₂ y ² + C ₂₀ x ² + C ₀₃ y ³ + C ₂₁ x ² y + C ₀₄ y ⁴ + C ₂₂ x ² y ² + C ₄₀
includes an optical element in which is defined by x ^4, is characterized by comprising an entrance pupil on the object side of said curved reflecting surfaces of the optical element.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, a plurality of the curved surfaces are provided, and the plurality of curved surfaces sequentially deflect the light beam.

The invention of claim 5 is the invention of claim 1, 2, 3, or 4.
The present invention is characterized by having a curved refraction surface.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the reflecting surface is provided on a surface of a surface reflecting mirror.

According to a seventh aspect of the present invention, in the fifth aspect, the reflection surface is provided on a surface of a transparent body.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, a stop is provided on the object side of the optical element.

According to a ninth aspect of the present invention, there is provided an imaging apparatus including the optical system according to any one of the first to eighth aspects.

According to a tenth aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
The optical system according to any one of the above items 9 to 9 is provided.

[0050]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments, the way of expressing the configuration data of the embodiments and the common items of the entire embodiments will be described.

FIG. 1 is an explanatory diagram of a coordinate system that defines the configuration data of the optical system according to the present invention. In the embodiment of the present invention, the i-th surface is defined as the i-th surface along one light ray (shown by a dashed line in FIG. 1 and referred to as a reference axis light ray) traveling from the object side to the image plane.

In FIG. 1, the first surface R1 is a stop (or entrance pupil), the second surface R2 is a refracting surface coaxial with the first surface, and the third surface R3 is a reflecting surface tilted with respect to the second surface R2. , 4th surface R4, 5th surface
R5 is a reflective surface shifted and tilted for each front,
The sixth surface R6 is a refracting surface shifted and tilted with respect to the fifth surface R5. Each surface from the second surface R2 to the sixth surface R6 is formed on one optical element made of a medium such as glass or plastic, and is referred to as a first optical element B1 in FIG.

Therefore, in the configuration shown in FIG. 1, the medium from the object surface (not shown) to the second surface R2 is air, the medium from the second surface R2 to the sixth surface R6 is a common medium, and the medium from the sixth surface R6 to the second surface R6 is not shown. The medium up to the seventh surface R7 is composed of air.

Since the optical system of the present invention is a decentered optical system, the surfaces constituting the optical system do not have a common optical axis. Therefore, in the embodiment of the present invention, first, an absolute coordinate system having the origin at the center of the effective beam diameter of the first surface (or entrance pupil) is set.

In the embodiment of the present invention, the first
The center point of the effective beam diameter of the surface (or entrance pupil) is defined as the origin, and the path of a light beam (reference axis light beam) passing through the origin and the center of the final imaging plane is defined as the reference axis of the optical system. further,
The reference axis in this embodiment has a direction (direction). The direction is the direction in which the reference axis ray travels during imaging.

In the embodiment of the present invention, the reference axis serving as the reference of the optical system is set as described above. However, how to determine the reference axis of the optical system depends on optical design, integration of aberrations, or optical system. It is only necessary to adopt an axis that is convenient for expressing each surface shape that constitutes. However, in general, the path of the light beam passing through the center of the image plane and either the stop, the entrance pupil or the exit pupil, or the center of the first surface or the center of the last surface of the optical system is referred to as a reference axis serving as a reference of the optical system. Set to.

In other words, in the embodiment of the present invention, the reference axis passes through the first surface, that is, the center point of the effective beam diameter of the stop surface (or entrance pupil), and reaches the center of the final imaging plane (reference axis). The path along which the light beam is refracted and reflected by each refraction surface and reflection surface is set as a reference axis. The order of each surface is set in the order in which the reference axis rays are refracted and reflected.

Accordingly, the reference axis finally reaches the center of the image plane while changing its direction along the set order of each surface according to the law of refraction or reflection.

The tilt surfaces constituting the optical system of each embodiment of the present invention are basically all tilted in the same plane. Therefore, each axis of the absolute coordinate system is determined as follows.

Z axis: Reference axis toward the second surface R2 passing through the origin Y axis: Straight line passing through the origin and forming 90 ° counterclockwise with respect to the Z axis in the tilt plane (in the paper of FIG. 1) : Straight lines passing through the origin and perpendicular to each of the Z and Y axes (straight lines perpendicular to the plane of FIG. 1). Also, to express the surface shape of the i-th surface that constitutes the optical system, the shape of that surface in the absolute coordinate system , The reference axis and the i-th
The configuration data of the present invention is displayed because it is easier to understand the shape of the surface by setting the local coordinate system having the origin at the point where the surface intersects and expressing the surface shape of the surface in the local coordinate system. In the embodiment, the surface shape of the i-th surface is represented by a local coordinate system.

The tilt angle of the i-th surface in the YZ plane is an angle θ with the counterclockwise direction being positive with respect to the Z axis of the absolute coordinate system.
i (unit: °). Therefore, in the embodiment of the present invention, the origin of the local coordinates of each surface is on the YZ plane in FIG. Also
There is no plane eccentricity in the XZ and XY planes. Further, the y, z axes of the local coordinates (x, y, z) on the ith plane are inclined at an angle θi in the YZ plane with respect to the absolute coordinate system (X, Y, Z). Set as follows.

Z-axis: an angle θ that passes through the origin of the local coordinate system and is counterclockwise in the YZ plane with respect to the Z direction of the absolute coordinate system
i-axis straight line y-axis: straight line passing through the origin of local coordinates and making 90 ° counterclockwise in the YZ plane with respect to z-direction x-axis: straight line passing through the origin of local coordinates and perpendicular to the YZ plane Di is a scalar quantity representing the distance between the origin of the local coordinates of the i-th surface and the (i + 1) -th surface, and Ndi and νdi are the i-th and (i + 1) th surfaces.
+1) The refractive index and Abbe number of the medium between the surfaces.

In the optical system according to the embodiment of the present invention, the entire focal length is changed (magnification is changed) by moving a plurality of optical elements. In the embodiment that gives numerical data of the present invention, the wide-angle end
(W), a sectional view of the optical system at three positions of the telephoto end (T) and an intermediate position (M) thereof, and numerical data are shown.

Here, in the optical element shown in FIG. 1, when the optical element moves in the YZ plane, the value changes at each magnification position at the origin (Yi, Zi) of the local coordinates representing the position of each plane.
In the embodiment in which the numerical data is given, the optical element that moves for zooming is expressed only as the movement in the Z direction, so the coordinate value Zi is given by the optical system in the order of the wide-angle end, the middle, and the telephoto end.
(W), Zi (M), and Zi (T).

Note that the coordinate values of each surface indicate values at the wide-angle end, and are described as differences from the wide-angle end at the middle and telephoto ends. Specifically, assuming that the movement amounts at the intermediate position (M) and the telephoto end (T) with respect to the wide-angle end (W) are Ma and Mb, respectively, they are represented by the following equations: Zi (M) = Zi (W) + Ma Zi (T) = Zi (W) + Mb The signs of Ma and Mb are positive when each surface moves in the Z plus direction, and negative when it moves in the Z minus direction. The surface distance Di that changes with this movement is a variable, and the values at each magnification position are shown in a separate table.

The embodiment of the present invention has a spherical surface and a rotationally asymmetric aspheric surface. Spherical portion of which I wrote the radius of curvature R _i as a spherical shape. The sign of the radius of curvature R _i is first
The case where the center of curvature is on the first surface side along the reference axis (dashed line in FIG. 1) that advances from the surface to the image surface is defined as minus, and the case where it is on the imaging surface side is defined as plus.

Here, the spherical surface has a shape represented by the following equation:

[0068]

(Equation 1)

The optical system of the present invention has at least one rotationally asymmetric aspherical surface, and its shape is represented by the following equation (where a, b, and t are coefficients relating to the shape): A = ( a + b) ・ (y ²・ cos ² t + x ² ) B = 2a ・ b ・ cos t [1 + {(ba) ・ y ・ sin t / (2a ・ b)} + [1 + {(ba ) ・ Y ・ sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t +
(a + b) ² sin ² t} x ² / (4a ² b ² cos ² t)] ^1/2 ] and z = A / B + C ₀₂ y ² + C ₂₀ x ² + C ₀₃ y ³ + C ₂₁ x ² y + C ₀₄ y ⁴ + C ₂₂ x ² y ² + C ₄₀
Since x ⁴ above curved surface expression is only even-order terms with respect to x, the curved surface defined by the equation for curved surface is a surface-symmetrical shape to the yz plane as the symmetry plane. Further, when the following condition is satisfied, the shape is plane-symmetric with respect to the xz plane. Therefore, when the following conditions are not satisfied, the shape is not plane-symmetric with respect to the xz plane, and there is only one plane of symmetry, the yz plane, and not more than two planes.

[0070] If the _{C 03 = C 21 = t =} 0 Furthermore _{C 02 = C 20 C 04 =} C 40 = C 22/2 is satisfied represents a rotation-symmetrical shape. If the above conditions are not satisfied, the shape is non-rotationally symmetric.

In each embodiment of the present invention, as shown in FIG. 1, the first surface (the entrance side of the optical system) is a stop. Also, the horizontal half-angle of view u _Y aperture in the YZ plane of FIG. 1 R1
Maximum angle of the light beam incident to, the vertical half angle u _X is the maximum field angle of a light beam incident on the stop R1 in the XZ plane. Also,
The diameter of the stop, which is the first surface, is shown as the stop diameter. This is related to the brightness of the optical system. Since the entrance pupil is located on the first surface, the aperture diameter is equal to the entrance pupil diameter.

The effective image area on the image plane is shown as an image size. The image size is represented by a rectangular area in which the size in the y direction of the local coordinates is horizontal and the size in the x direction is vertical.

Further, in the embodiment in which the configuration data is listed, the size of the optical system is shown. The size is a size determined by the effective beam diameter at the wide-angle end.

The lateral aberration chart is shown for the embodiment in which the configuration data is listed. The lateral aberration diagram shows the wide-angle end of each embodiment.
(W), middle position (M), and telephoto end (T).
The horizontal and vertical angles of incidence on R1 are (u _Y , u _X ), (0, u _X ),
_{(-u Y, u X),} (u Y, 0), (0,0), (- u Y, 0) and showing lateral aberration of the light flux incident angle made. In the lateral aberration diagram, the horizontal axis represents the height of incidence on the pupil, and the vertical axis represents the amount of aberration. In each embodiment, since each surface is basically a plane-symmetrical shape with the yz plane as a plane of symmetry, the plus and minus directions of the vertical angle of view are the same even in the lateral aberration diagram, so that the drawing is simplified. For this reason, a lateral aberration diagram in the minus direction is omitted.

The following Embodiments 1 to 4 are qualitative embodiments that do not give configuration data, and Embodiments 5 to 16 give configuration data.

In the first to fourth embodiments, a surface symbol and the like are assigned to each of the constituent optical elements regardless of the symbol nomenclature. That is, the aperture is B _L , the final image plane is P,
In the M-th optical element, R _{m, 1} , R _{m, 2} ,... R
_The symbols _{m and n} are attached.

[Embodiment 1] FIG. 2 is a schematic view of a main part of Embodiment 1 of the present invention. This embodiment is an embodiment of an imaging optical system of a so-called two-unit type zoom lens. In the figure, B1 and B2 are first and second optical elements having a plurality of curved reflecting surfaces. The first optical element B1 is, in order from the object side, a concave refractive surface R _1,1
And concave mirror R _1,2 , convex mirror R _1,3 , concave mirror R _1,4 , convex mirror R _1,5
Consists of four reflecting surfaces and the convex refracting surface R _{1, 6,} and the direction of the reference axis which now emitted and the direction of the reference axis entering the first optical element B1 is parallel to and the same direction (orientation).

The second optical element B2 has a convex refractive surface R from the object side.
_2,1 and convex mirror R _2,2・ concave mirror R _2,3・ convex mirror R _2,4・ concave mirror R
₂ , 4 reflecting surfaces and a convex refracting surface R2, ₆ and, like the first optical element B1, the direction of the reference axis incident on the second optical element B2 and the direction of the reference axis emerging therefrom. Are parallel and in the same direction.

B3 is an optical correction plate composed of a parallel plate,
It is composed of a low-pass filter and an infrared cut filter made of quartz.

P is an image pickup device surface which is a final image surface, for example, an image pickup surface of a CCD (image pickup medium) or the like. B _L is a stop disposed on the object side (light beam incident side of the optical system) of the first optical element B1, and A _i is a reference axis of the imaging optical system.

The first optical element B1 and the second optical element B2 constitute one element of a two-unit zoom lens.

Next, the image forming operation in this embodiment will be described. Beam from the object 8, after being regulated quantity of incident light by the diaphragm B _L, incident on the concave refracting surface R _{1, 1} of the first optical element B1.

Next, the light flux refracted and transmitted through the concave refraction surface R _1,1 is
The light is reflected by the concave mirrors R1, ₂ and forms an image on the primary imaging surface N1 by the power of the concave mirror.

As described above, once forming an object image in the first optical element B1, it is effective to suppress an increase in the effective beam diameter of the surface arranged on the image side of the stop _BL. .

The light beam primarily formed on the primary image forming surface N1 is repeatedly reflected by the convex mirrors R _1,3 , the concave mirrors R _1,4 and the convex mirrors R _1,5 .
In response to converging or diverging action by the power of each reflecting mirror, reaches the convex refracting surface R _{1, 6,} luminous flux refracted here forms an object image on the secondary image forming plane N2.

As described above, the first optical element B1 functions as a lens unit having desired optical performance and having positive power as a whole by repeating refraction by the input / output surface and reflection by a plurality of curved reflecting mirrors. ing.

The luminous flux from the object image on the secondary imaging plane N2 is
After passing through the convex refraction surface _R2,1 of the optical element B2, the convex mirror
An image is formed on a tertiary imaging plane N3 via R _2,2 and a concave mirror R _2,3 .

This is for the same reason that the object image is formed in the first optical element B1.
This is effective for suppressing an increase in the effective beam diameter of each surface in B2.

The light beam formed on the tertiary image forming surface N3 is a convex mirror.
R _2,4 , the reflection is repeated by the concave mirror R _2,5 , and is affected by the power of each reflecting mirror to reach the convex refraction surface R _2,6 , where the refracted light flux passes through the optical correction plate B3 After passing, an image is formed on the imaging element surface P.

As described above, the second optical element B2 converts the object image formed on the secondary imaging plane N2 by the first optical element B1 into the image pickup element surface.
P is re-imaged on P, and similarly to the first optical element B1, refraction by the input / output surface and reflection by a plurality of curved reflecting mirrors are repeated to provide a desired positive optical performance as a whole. It functions as a lens unit having power.

In this embodiment, the first and second
By moving the optical elements B1 and B2 relative to the imaging element plane (imaging plane) P2, the focal length (imaging magnification) of the photographing optical system is changed. (This is an operation called zooming or zooming.) The zooming operation will be described with reference to FIG. FIG. 3 shows the first and second optical elements B1 and B2 of the first embodiment.
Are optical arrangement diagrams in which each is a single thin lens, and an imaging optical system is developed with respect to its reference axis. Note that FIG.
FIG. 3 is a layout diagram of the optical system at the wide-angle end (W).
(B) is a layout diagram in the state (T) at the telephoto end.

In the figure, the focal length of the first optical element B1
Release the f₁, The focal length of the second optical element B2_Two, And. light
When the optical system is at the wide-angle end, the front focus of the second optical element B2 is
Point F _Two X to the secondary imaging plane N2_W(-), Rear focus F
_TwoX is the distance from the imaging plane P to_W'. (In addition, below
Subscripted_WAnd_TIndicates that the optical system is at the wide-angle end and the telephoto end, respectively.
Means the value. ) According to Newton's imaging formula x_W* X_W'= -F_Two ^Two Holds, the imaging magnification of the second optical element B2
β_2WIs β_2W= − (X_W'+ F_Two) / (− X_W+ F_Two) = F_Two/ x_W = −x_W'/ f_Two (1) and the focal length f at the wide-angle end_WIs f_W= F₁* β_2W = F₁* f_Two/ x_W (2).

Here, the second optical element B2 moves while satisfying the Newton's image forming formula, and the second optical element B2 corrects the change in position of the intermediate imaging plane N2 accompanying the movement of the second optical element B2. As the one optical element B1 moves, the optical system changes the focal length without changing its final imaging position P 1.

It is assumed that the second optical element B2 moves by a certain amount and changes the magnification from the wide-angle end (W) to the telephoto end (T). The distance from the front focal point F2 of the _second optical element B2 to the intermediate image plane N2 is x
_T (-), when 'the distance from to the imaging surface P x _T' rear focal point F ₂ a, the imaging magnification beta _2T of the second optical element _{B2, β 2T = (x T '} + f 2) _{/ (-x T + f 2)} = f 2 / x T = -x T '/ f 2 (3), _: focal length f _T of the telephoto _{end, f T = f 1 * β} 2T = f 1 * f 2 / x _T (4), so that the zoom ratio Z of this optical system is Z = f _T / f _W = x _W / x _T (5)

As described above, by changing the relative positional relationship between the first optical element B1 and the second optical element B2 and between the second optical element B2 and the imaging element surface P, the final image forming position P It is possible to change the focal length (imaging magnification) without changing.

Next, in the first embodiment, focusing can be achieved by moving an arbitrary optical element constituting the optical system. However, considering the load on the actuator for focusing, the weight is the largest. It is preferable to move the light optical element.

When it is desired to keep the moving amount of the optical element constant with respect to the distance to the subject to be photographed regardless of the magnification,
What is necessary is just to move the 1st optical element B1 arrange | positioned at the object side most.

The second optical element B2 that moves during zooming
By moving the lens during focusing, it is possible to make the actuator for zooming and the actuator for focusing common.

The effects of this embodiment will be described.

In this embodiment, since the reflecting surface that moves during zooming is unitized, the relative positional accuracy of each reflecting surface, which is most required in the conventional mirror optical system, is guaranteed. . Therefore, in the present embodiment, the positional accuracy between the first optical element B1 and the second optical element B2 may be ensured, and the same positional accuracy as that of the moving lens group in the conventional refractive lens system is sufficient.

Since each optical element is configured as a lens unit integrally formed with a plurality of curved reflecting surfaces as compared with a refractive lens system, the number of parts of the entire optical system is reduced, and The cost can be reduced, and the accumulated error due to the mounting of the components is reduced.

By adopting a configuration in which an object image is transmitted while performing image formation a plurality of times, the effective beam diameter of each surface is reduced, and the size of each optical element and the entire photographing optical system is reduced. I have.

Further, by setting the image size of the intermediate image to be relatively small with respect to the size of the image sensor surface, the effective beam diameter of each surface when transmitting an object image is kept small.

In the case of a conventional photographing optical system, the diaphragm is often arranged inside the optical system. When the diaphragm is arranged inside the optical system, the effective beam diameter of the lens arranged on the object side of the diaphragm is large. However, there is a problem that as the distance from the aperture increases, the distance increases with an increase in the angle of view.

In the present embodiment, the focal length of the photographing optical system is widened by installing the stop (entrance pupil) B _L near the incident surface of the first optical element B1 on the object side of the photographing optical system. This suppresses the enlargement of the effective beam diameter of the front group of the imaging optical system, which sometimes occurs.

By forming an object image in each optical element, an increase in the effective beam diameter of the surface arranged on the image side of the stop _BL is effectively suppressed.

The reference axes of the first optical element B1 and the second optical element B2 are all in the YZ plane. Therefore, by setting the movement of each optical element on a plane parallel to the YZ plane, even if the first optical element B1 and the second optical element B2 move at the time of zooming, the movement of the first optical element B1 and the second optical element B2 is not changed. The parallelism with the plane on which each optical element moves is easily maintained, and it is easy to eliminate the parallel eccentricity of the optical elements B1 and B2 in the X-axis direction and the rotation around the Y-axis and Z-axis.

However, even if the YZ plane including the reference axis and the plane on which both optical elements move are inclined, if the direction vector on which the YZ plane including the reference axis moves upon zooming is parallel to the moving plane, the eccentricity will occur. No aberration occurs.

Since each optical element is arranged on one plane, a structure for incorporating each optical element from one direction can be easily obtained, and assembly becomes very easy.

In this embodiment, the secondary imaging plane N2 is the first
Although it is formed between the optical element B1 and the second optical element B2, a secondary image plane may be provided inside the first optical element B1 or the second optical element B2.

The moving direction of the optical element at the time of zooming should minimize the error that occurs at the time of zooming unless the incident point position of the reference axis of each reflecting surface is changed when moving from the wide-angle end to the telephoto end. Incident on each of the optical elements B1 and B2,
The direction of the reference axis to be emitted is made parallel, and the movement of each optical element also moves in parallel along the reference axis line that enters and exits the optical element.

In the present invention, when an optical element having a reference axis direction which enters and exits each optical element is parallel to each other, it is necessary to set the exit direction to the same direction or the opposite direction to the incident direction. Different patterns are possible. When the exit direction is opposite to the incident direction, the distance between the entrance side and the exit side changes by the same amount as the movement amount due to the movement of the optical element. Therefore, the optical path length is twice the movement amount as a whole. Can be changed.

When the emission direction is the same as the incidence direction, it is possible to shift the position of the input reference axis and the output reference axis to a desired position.

Since the embodiment of the present invention can be constituted by the above two types of patterns, the present invention can increase the degree of freedom in optical arrangement.

However, the moving direction of the optical element does not need to be parallel to the directions of the reference axes that enter and exit the two optical elements. For example, the direction of the reference axis that enters the optical system and the moving direction of the moving optical element are different. , 30 °, 45 °, 60 ° or the like.

[Embodiment 2] FIG. 4 is a schematic view of a main part of Embodiment 2 of the present invention. This embodiment is an embodiment of an imaging optical system of a so-called two-unit type zoom lens. This embodiment is an embodiment in which the moving direction of the optical element that moves during zooming is not parallel to the direction of the incident reference axis of the optical element arranged closest to the object side.

In the figure, B1 and B2 denote a plurality of curved reflecting surfaces.
First and second optical elements. First optical element B1
Is the concave refractive surface R in order from the object side._1,1And concave mirror R_1,2·convex
Mirror R _1,3 ・ Concave mirror R_1,4・ Concave mirror R_1,5Four reflective surfaces and
Convex refraction surface R_1,6Consists of an overall positive refractive power
It is a lens unit. Then, it enters the first optical element B1.
The direction of the reference axis to be emitted and the direction of the
Has a 45 ゜ inclination.

The second optical element B2 has a concave refractive surface R from the object side.
_2,1And concave mirror R_2,2・ Concave mirror R_2,3・ Convex mirror R_2,4・ Concave mirror R
_2,5・ Concave mirror R_2,6・ Concave mirror R_2,76 reflective surfaces and convexity
Folded surface R _2,8 Having a positive refractive power as a whole.
Unit. Then, the light enters the second optical element B2.
The direction of the reference axis to be emitted is parallel to the direction of the reference axis to be emitted
And in the opposite direction.

B3 is an optical correction plate made of a parallel plate,
Examples include a quartz low-pass filter and an infrared cut filter.

P is an image sensor surface, and is a CCD (imaging medium)
And the like. B _L denotes a stop arranged on the object side of the first optical element B1, and A _i denotes a reference axis of the optical system.

The image forming operation of this embodiment will be described. Beam from the object is squeezed after being regulated quantity of incident light by (entrance pupil) B _L, and refracting and transmitting the concave refracting surface R _{1, 1} of the first optical element B1,
The reflection is repeated by the concave mirror R _1,2 , the convex mirror R _1,3 , the plane mirror R _1,4 , and the concave mirror R _1,5 . _The light fluxes refracted here form an object image on the intermediate imaging plane N1.
Note that an intermediate image of the object is once formed even in the first optical element B1.

The light beam from the object image on the intermediate imaging plane N1 is
After passing through the concave refracting surface R _2,1 of the optical element B2, the concave mirror
R _2,2 , concave mirror R _2,3 , convex mirror R _2,4 , concave mirror R _2,5 , concave mirror R
_2,6, via the concave mirror R _{2, 7} emitted from the second optical element B2 is refracted convex refracting surface R _{2, 8.} Note that an intermediate image of the object is once formed in the second optical element B2.

The light beam emitted from the second optical element B2 passes through the optical correction plate B3 and forms an image on the image pickup element surface P.

In this embodiment, focusing for different object distances is performed by moving the second optical element B2. At this time, the movement of the second optical element B2 moves parallel to the direction of the reference axes A1 and _A6 emitted from the first optical element B1, but the reference axis to which the first optical element B1 is incident.
For the direction of the reference axis A _{1, 6} to emit the direction of A ₀ is that a substantially 45 ° inclination with respect to the direction of the reference axis A ₀ which enters the first optical element B1, the second optical The direction in which the element B2 moves during focusing is inclined by approximately 45 °.

Accordingly, the second optical element B2 moves parallel to the direction of the reference axes A _1,6 , A _{2,8 which enter} and exit the focusing element, but _enter the first optical element B1 during focusing. for the direction of the reference axis a ₀ moves with the 45 ° inclination.

Also, in this embodiment, the first and second optical elements B1 and B2 move relative to the image plane P, as in the first embodiment, so that the imaging magnification of the photographing optical system is increased. To change. However, the first embodiment in which the direction of the reference axis that enters and exits each optical element and the moving direction of each optical element were all parallel.
Unlike the first optical element B1, the direction of the reference axis incident on the first optical element B1 and the direction of the reference axis emerging therefrom have an inclination of 45 °. Optical element
In order to maintain the direction of the reference axis incident on B2, the moving direction of the first optical element B1 is moved parallel to the direction of the incident reference axis of the second optical element B2.

[Embodiment 3] FIG. 5 is a schematic view of a main part of Embodiment 3 of the present invention. This embodiment is an embodiment of an imaging optical system of a so-called two-unit type zoom lens. In the figure, B1 and B2 are first and second optical elements having a plurality of curved reflecting surfaces. The first optical element B1 is, in order from the object side, a concave refractive surface R _1,1
And concave mirror R _1,2 , convex mirror R _1,3 , concave mirror R _1,4 , convex mirror R _1,5
It consists of four reflecting surfaces and the concave refracting surface R _{1, 6,} and a lens unit having a negative refractive power as a whole. Then, a direction and the same direction parallel to the reference axis A _{1, 6} which will now be emitted to the direction of the reference axis A ₀ which enters the first optical element B1 in the same manner as in Example 1.

The second optical element B2 has a convex refractive surface R from the object side.
_2,1 and convex mirror R _2,2・ concave mirror R _2,3・ convex mirror R _2,4・ concave mirror R
_The lens unit is composed of four reflecting surfaces _2,5 and a convex refracting surface _R2,6 and has a positive refractive power as a whole. And a first direction and in the same direction parallel to the reference axis A _{2, 6} which will now be emitted to the direction of the reference axis A _{1, 6} which enters the second optical element B2 as well as the optical element B1.

B3 is an optical correction plate composed of a parallel plate,
Examples include a quartz low-pass filter and an infrared cut filter.

P is an image sensor surface, and is a CCD (imaging medium)
And the like. B _L denotes a stop arranged on the object side of the first optical element B1, and A _i denotes a reference axis of the optical system.

The image forming operation of this embodiment will be described. Beam from the object is squeezed after being regulated quantity of incident light by (entrance pupil) B _L, and refracting and transmitting the concave refracting surface R _{1, 1} of the first optical element B1,
The reflection is repeated by the concave mirror R _1,2 , the convex mirror R _1,3 , the concave mirror R _1,4 , and the convex mirror R _{1,5, and the} convergence or divergence is given by the power of each reflecting mirror, and the concave refractive surface R _The light reaches the _{points 1} , ₆ where it is refracted and emitted from the first optical element B1. The first
Forms an intermediate image of the object once in the optical element B1.

Next, the light beam passes through the convex refraction surface R _2,1 of the second optical element B2, and then passes through the convex mirror R _2,2 , the concave mirror R _2,3 , and the convex mirror.
The reflection is repeated by R _2,4 and the concave mirror R _2,5 , and the convex refraction surface R _2,6 is refracted and emitted from the second optical element B2. Note that an intermediate image of the object is once formed in the second optical element B2.

The light beam emitted from the second optical element B2 passes through the optical correction plate B3 and forms an image on the image pickup element surface P.

In this embodiment, similarly to the first embodiment, the first optical element B1 and the second optical element B2 are moved relatively to the image plane P, so that the final image position P is moved. The focal length (imaging magnification) of the optical system is changed without changing.

The zooming operation of this embodiment will be described with reference to FIG. FIG. 6 is an optical arrangement diagram in which each optical element of the third embodiment is a single thin lens, and the optical system is developed with respect to its reference axis. FIG. 6A shows a state where the optical system is at the wide-angle end.
FIG. 6B is a layout view of FIG. 6B, and FIG. 6B is a layout view of the state at the telephoto end (T).

In the figure, the focal length of the first optical element B1 is f ₁ (−), and the focal length of the second optical element B2 is f ₂ .
When the optical system is at the wide-angle end, the distance from the front focal point F2 of the _second optical element B2 to the image point of the first optical element B1 is _xW (-).
If the distance from the rear focal point F ₂ ′ to the imaging plane P is x _W ′, if the Newton imaging formula x _W * x _W ′ = −f ₂ * f ₂ holds, The imaging magnification β _2W of the second optical element B2 is β _2W = − (x _W ′ + f ₂ ) / (− x _W + f ₂ ) = f ₂ / x _W = −x _W ′ / f ₂ (6) The focal length f _W at the wide-angle end is f _W = f ₁ * β _2W = f ₁ * f ₂ / x _W (7)

Here, the second optical element B2 moves while satisfying the Newton's imaging formula, and the change in the position of the object point of the second optical element B2 accompanying the movement of the second optical element B2 is corrected. As described above, by moving the first optical element B1, the optical system can change the entire focal length without changing the final imaging position P.

The second optical element B2 moves by a certain amount and spreads.
Suppose that the magnification has changed from the corner end (W) to the telephoto end (T). This telephoto
In the end state, the front focal point F of the second optical element B2_TwoFrom first
X is the distance to the image point of optical element B1_T(-), Rear focus F_Two'
X to the image plane P _T'Then the second optical element
Imaging magnification β of child B2_2TIs β_2T= (X_T'+ F_Two) / (− X_T+ F_Two) = F_Two/ x_T = −x_T'/ f_Two (8), focal length f at telephoto end_TIs f_T= F₁* β_2T = F₁* f_Two/ x_T (9) Therefore, the zoom ratio Z of the optical system is expressed as follows: Z = f_T/ f_W = X_W/ x_T (10)

In the first embodiment, the secondary imaging surface N2 exists between the first optical element B1 and the second optical element B2. In the present embodiment, however, the first optical element B1 as a whole is It has a negative refracting power, forms an image of an object light beam from infinity on the object side as a virtual image, and establishes the image forming relationship of the second optical element B2 with the position of the virtual image as an object point.

Contrary to the structure of the present embodiment, even when there is an optical element having a positive refractive power as a whole and an optical element having a negative refractive power behind the optical element in order from the object side, each optical element has By relatively moving the elements, the focal length (imaging magnification) of the photographing optical system can be changed.

[Embodiment 4] FIG. 7 is a schematic view of a main part of Embodiment 4 of the present invention. This embodiment is an embodiment of an imaging optical system of a so-called three-group zoom lens. In the figure, B1, B2,
B3 is a first, second, and third optical element each having a plurality of curved reflecting surfaces, and the first optical element B1 is arranged in order from the object side.
Concave refracting surface R _{1, 1} and the concave mirror R _{1, 2} · convex mirror R _{1, 3} · concave mirror R _{1, 4}
Reference axis of consists three reflecting surfaces and the convex refracting surface R _{1, 5,} has a positive refractive power as a whole, is incident on the first optical element B1
Direction of the reference axis A _{1, 5} which will now be emitted to the direction of A ₀ are substantially perpendicular.

The second optical element B2 has a plane R _2,1 and a concave mirror R _2,2 · a plane mirror R _2,3 · a convex mirror R _2,4 · a plane mirror R _2,5 · from the object side.
_Consists of five reflecting surfaces of concave mirrors _R2,6 and plane _R2,7 , has a positive refracting power as a whole, the direction of reference axes _A1,5 incident on the second optical element B2, and the reference emitted therefrom. The directions of the axes A2 and _A7 are parallel and opposite.

The third optical element B3 is convex and concave in order from the object side.
Folded surface R_3,1And convex mirror R_3,2・ Concave mirror R _3,3 ・ Concave mirror R_3,4・
Convex mirror R_3,5Four reflective surfaces and concave refraction surface R_3,6Consisting of
Positive refractive power as a whole, incident on the third optical element B3
Reference axis A_2,7Direction and reference axis A to be emitted_3,6of
The directions are parallel and the same direction.

A fourth optical element B4 is a triangular prism composed of, in order from the object side, a convex refracting surface R _4,1 , a plane mirror R _4,2 , and a plane R _4,3. Reference axis A incident on
The directions of _3,6 and the reference axes A _{4,3 to be} emitted from now are substantially perpendicular.

B5 is an optical correction plate composed of a parallel plate,
Examples include a low-pass filter and an infrared cut filter made of quartz.

P is an imaging element surface, for example, an imaging surface of a CCD (imaging medium) or the like. B _L denotes a stop arranged on the object side of the first optical element B1, and A _i denotes a reference axis of the present optical system.

An image forming operation in the present embodiment will be described. The light beam from the object is first restricted in the amount of incident light by the stop (entrance pupil) _BL , and then enters the first optical element B1. The first optical element B1 has an exit surface _R1,5 and an entrance surface of the second optical element B2.
To form a primary image forming plane N1 between R _2,1.

The object image formed on the primary imaging plane N1 is
The exit surface _R2,7 of the optical element B2 and the third optical element B3
It is reimaged on a two image forming plane N2 between the incident surface R _{3, 1} of.

[0149] And also, the object is formed on an intermediate image plane N2 image between the incident surface R _{4, 1} of the third by the optical element B3 and its exit surface R _{3, 6} a fourth optical element B4 The image is re-imaged on the tertiary imaging plane N3.

The fourth optical element B4 converges the light beam from the object image formed on the tertiary imaging plane N3 and forms an image on the imaging element plane P via the optical correction plate B5.

In this embodiment, in particular, in order to shorten the length in the Z direction in FIG. 7, the optical path is effectively folded by each optical element, and the arrangement in which the length in the Z direction is significantly reduced is adopted. .

[0152] That is, after the incident light beam incident on the first optical element B1 on the concave refracting surface R _{1, 1,} the concave mirror disposed behind R
Due to _{1 and 2} , the light is reflected in the direction perpendicular to the incident direction, that is, in the Y (-) direction.

[0153] Next convex mirror R _{1, 3} by an object beam Z (-) is reflected in the direction to shorten the length of the Z-axis direction of the optical system.

The object beam reflected in the Z (-) direction is a concave mirror R
After being reflected in the Y (-) direction again by _1,4 , the convex refraction surface R _1,5
And is incident on the second optical element B2.

[0155] In the second optical element B2, it constitutes so as to total reflection object light at the plane R _2,3 and the plane R _{2, 5,}
The effective ray area on the entrance surface R _2,1 of the second optical element B2 and the effective ray area on the plane R _2,3 overlap,
Further, the length of the optical element in the Z-axis direction is shortened by overlapping the effective ray area on the exit surface _R2,7 of the second optical element B2 with the effective ray area on the plane _R2,5 . .

Then, the object light beam incident on the second optical element B2 from the Y (-) direction exits in the Y (+) direction, and exits from the third optical element B3.
Incident on.

In the third optical element B3, the object light beam is a convex mirror.
After being reflected in the Z (-) direction at R _3,2 and not interfering with the first optical element B1, after being reflected in the Y (+) direction by the concave mirror R _3,3 , the concave mirror R _3,4 Return to Z (+) direction at
Incident at an incident point substantially the same Z-position of the _3,2, is reflected in the Y (+) direction by the convex mirror R _{3, 5,} the concave refracting surface passes through the R _{3, 6} fourth optical element B4 I do.

In the fourth optical element B4, the object light beam is a plane mirror R
After being reflected in the Z (-) direction by _{4 and 2} , the light passes through the optical correction plate B5 and forms an image on the imaging element surface P.

The first, second, and third optical elements B of this embodiment
Reference numerals 1, B2 and B3 constitute one element of a so-called three-group zoom lens. Then, the focal length (imaging magnification) of the photographing optical system is changed by relatively moving the second optical element B2 and the third optical element B3.

The scaling operation in this embodiment will be described. During zooming, the first optical element B1, the fourth optical element B4, the optical correction plate B5, and the imaging plane P are fixed, and the second optical element B2 and the third optical element B3 are moved.

At the time of zooming from the wide-angle end to the telephoto end, the second optical element B2 moves in the Y (-) direction away from the first optical element B1.

Although the distance between the optical elements B1 and B2 is widened, the direction of the reference axis of the second optical element B2 and the direction of the output reference axis of the second optical element B2 are parallel and opposite to each other. Unlike the first embodiment in which the incident reference axis and the exit reference axis are in the same direction, the distance between the optical elements B2 and B3 is also increased by the same amount as the distance between the optical elements B1 and B2. become.

That is, the moving amount of the second optical element B2 is δ
Then, even if the first optical element B1 and the imaging plane P are fixed during zooming, the entire length of the photographing optical system is twice as long as the moving amount δ of the second optical element B2.

FIG. 8 is an optical arrangement diagram in which each optical element of the fourth embodiment is a single thin lens, and the imaging optical system is developed with respect to its reference axis. The magnification operation will now be described. FIG. 8A is an arrangement diagram of the optical system at the wide angle end (W), and FIG. 8B is an arrangement diagram of the optical system at the telephoto end (T).

[0165] In the figure, the focal length f ₁ of the first optical element B1, the focal distance f ₂ of the second optical element B2, the focal length f ₃ of the third optical element B3, the fourth optics Set the focal length of element B4
f ₄

With the optical system at the wide-angle end, the second
Front focus F of optical element B2_TwoTo the primary imaging plane N1
To x_2W(-), Rear focus F_Two'To the secondary imaging plane N2
X _2W', The front focal point F of the third optical element B3_ThreeSecondary imaging from
X to distance to surface N2_3W(-), Rear focus F_Three'3rd imaging
X to distance to surface N3_3W', The front focal point F of the fourth optical element B4_Four
X to the tertiary imaging plane N3_Four(-), Rear focus F_Four'Or
X to the image plane P_Four'.

The imaging magnification of the second optical element B2 is β _2W ,
The imaging magnification of the third optical element is β _3W , and the imaging magnification of the fourth optical element B4 is β ₄ . (Note that the subscripts _W and _T represent the state of the optical system at the wide-angle end and the state of the telephoto end, respectively.) If Newton's imaging formula holds between each intermediate image and the imaging plane, the first The composite magnification β _W by the optical element behind the optical element B1 is β _W = β _2W * β _3W * β ₄ = (f ₂ / x _2W ) * (f ₃ / x _3W ) * (f ₄ / x ₄ ) = (F ₂ * f ₃ * f ₄ ) / (x _{2 W} * x _{3 W} * x ₄ ) (11), and the focal length f _W at the wide-angle end is f _W = f ₁ * β _W = (f ₁ * f ₂ * f ₃ * f ₄ ) / (x _2W * x _3W * x ₄ ) (12)

Here, a secondary image plane N2 generated when the second optical element B2 moves by δ with respect to the first optical element B1.
By moving the third optical element B3 by η so that the position of the tertiary imaging plane N3 is not changed by correcting the position of the tertiary imaging plane N3 in accordance with the position change of Can be changed.

In the optical arrangement at the telephoto end in FIG. 8B, the first optical element B1, which should be fixed in the developed view, is relatively moved by 2δ because of the fixed imaging plane P. This is illustrated as shown.

Since the second optical element B2 has moved by δ with respect to the first optical element B1, the distance x _2T from the primary imaging plane N1 to the front focal point F2 of the _second optical element B2. (−) Becomes x _2T = x _2W −δ (13).

Further, since the third optical element B3 is moved by η with respect to the tertiary imaging plane N3, the third optical element B3 moves from the tertiary imaging plane N3 to the third
The distance x _3T ′ to the rear focal point F ₃ ′ of the optical element B3 is x _3T ′ = x _3W ′ −η = − (f ₃ ² / x _3W + η) (14)

Further, the distance x _2T ′ −x _3T from the rear focal point F ₂ ′ of the second optical element B2 to the front focal point F _{3 of} the third optical element B3.
Since the total length of the photographing optical system is longer 2.delta., The _{x 2T '-x 3T = x 2W} ' -x 3W + δ + η = -f 2 2 / x 2W -x 3W + δ + η (15).

X _2T ′ and x _3T in the equation (15) are obtained by using the equations (13) and (14) as x _2T ′ = −f ₂ ² / x _2T = −f ₂ ² / (x _2W −δ ) (16) since ^{_{x 3T = -f 3 2 / x}} 3T '= (f 3 2 * x 3W) / (f 3 2 + x 3W * η) become (17), equation (15), -f _{2 ^{2 / (x 2W -δ) -}} (f 3 2 * x 3W) / (f 3 2 + x 3W * η) = -f 2 2 / x 2W -x 3W + δ + η (18) , and the equation (18) the The movement relationship of the third optical element B3 with respect to the movement of the second optical element B2 can be expressed.

In the present embodiment, the focal length f _T at the telephoto end after the movement of the optical element is such that the composite magnification β _T of the optical element disposed closer to the image plane than the first optical element B 1 is β _T = β _2T * β _3T * β ₄ = (f ₂ / x _2T ) * (f ₃ / x _3T ) * (f ₄ / x ₄ ) = (f ₂ * f ₃ * f ₄ ) / (x _2T * x _3T * x ₄ ) (19), so that f _T = f ₁ * β _T = (f ₁ * f ₂ * f ₃ * f ₄ ) / (x _2T * x _3T * x ₄ ) = f ₁ * f ₂ * f ₃ * f ₄ * (f ₃ ² + x _3W * η) / {(x _2W −δ) * f ₃ ² * x _3W * x ₄ } (20)

[0175] zoom ratio Z of this by the photographing optical system _{is, Z = f T / f W} = x 2W * x 3W / (x 2T * x 3T) = x 2W * x 3W * (f 3 2 + x 3W * eta) / a _{{(x 2W -δ) * f} 3 2 * x 3W} = x 2W * (f 3 2 + x 3W * η) / {(x 2W -δ) * f 3 2} (21).

In this embodiment, as described above, the length of the optical system in the Z direction is significantly shortened by the configuration in which the optical path is effectively folded by each optical element. Further, since the shape of the third optical element B3 is made to fill the dead space behind the first optical element B1, there is no spatial waste in the arrangement of all the optical elements.

Further, the second optical element B2 and the third optical element B3 are moved in the Y-axis direction at the time of zooming, so that the length in the Z-axis direction is kept small in all zooming areas. It is held down.

In this embodiment, the reference axis which enters the direction of the reference axes A _{4 and 3} emitted from the fourth optical element B 4 is used.
The reference axis but bent 90 degrees to the direction of A _{3, 6,} which emits
The directions and angles of A3 and _A6 are not limited in this way. For example, a reflective surface may be provided and bent in a direction perpendicular to the paper surface (X direction).

[0179] Also, the direction of the reference axis A ₀ which enters the optical system, disposed 45 ° mirror or the like for example on the object side of the aperture B _L, may be incident reference axis A ₀ from the vertical to the paper surface .

Further, in this embodiment, since the first optical element B1 is fixed during zooming, the reflection surface for bending the first optical element B1 and the reference axis on which the first optical element B1 is incident may be integrally formed in advance.

[0181] In all of the following embodiments, configuration data is attached. The fifth to twelfth embodiments are zoom lenses having a two-group configuration similar to the first embodiment, and the thirteenth to sixteenth embodiments are zoom lenses having a three-group configuration including three optical elements.

In these embodiments, the reflecting surface constituting the optical system is a surface having different curvatures in the plane of the paper and in the direction perpendicular to the plane of the paper. Eccentric aberration caused by eccentric arrangement is corrected.

Further, by making this reflection surface a rotationally asymmetric surface, various aberrations are corrected well, and a desired optical performance is achieved in each optical element.

[Embodiment 5] FIG. 9 shows a YZ plane according to Embodiment 5 of the present invention.
It is an optical cross section in a plane. This embodiment is an imaging optical system of a zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0185]

[Outside 1]

[0186]

[Outside 2]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil, the second surface R2 to the fifth surface R5, and the sixth surface R6 to the ninth surface.
R9 is an integrated first and second optical element B1, B2, and a tenth surface R10 is an image surface.

Hereinafter, the image forming operation when the object position is at infinity will be described. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1. In the first optical element B1, refraction occurs on the second surface R2, the third surface R3, the fourth surface R4.
And is refracted by the fifth surface R5, and exits the first optical element B1. At this time, a primary image is formed on an intermediate image forming surface near the fourth surface.

Next, the light beam enters the second optical element B2. In the second optical element B2, refraction occurs on the sixth surface R6, and the seventh surface R7 and the eighth surface R8
And is refracted by the ninth surface R9, and exits the second optical element B2. At this time, a pupil is formed near the seventh surface in the second optical element B2. The light beam emitted from the second optical element B2 finally forms an image on the tenth surface R10 (the imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and the same direction. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and the same direction.

Next, a description will be given of the zooming effect due to the movement of each optical element. Upon zooming, the first optical element B1 once moves in the Z plus direction from the wide-angle end to the telephoto end, and
Move in the minus direction. The second optical element B2 moves in the Z minus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the image plane R10 is increased.

FIGS. 10, 11, and 12 are lateral aberration diagrams of the present embodiment. These lateral aberration diagrams angle of incidence of the light beam to the present embodiment is respectively _{(u Y, u X),} (0, u X), (- u Y, u X), (u Y, 0), (0 , 0), (-u _Y , 0)
The lateral aberrations in the Y direction and the X direction are shown for the six light beams. The horizontal axis of each lateral aberration diagram is the incident height of the incident light beam in the Y direction and the X direction on the first surface, respectively.

FIG. 10 is a lateral aberration diagram at the wide angle end (W) of this embodiment, FIG. 11 is a lateral aberration diagram at an intermediate position (M), and FIG. 12 is a telephoto end.
It is a lateral aberration figure of (T).

In this embodiment, as can be seen from the drawing, balanced aberration correction is obtained in each state.

In this embodiment, assuming that the image size is 4 × 3 mm, the length, width and thickness of the optical system are 32.9 × 21.4 × 6.6 mm.
Size and compact. In particular, in this embodiment, the thickness of each optical element and the entire optical system is small,
In addition, since each optical element can be configured by forming a reflection surface on the side surface of a plate-like block, a mechanism for moving two optical elements along a substrate surface on one substrate can provide a thin zoom lens as a whole. Can be easily configured.

[Embodiment 6] FIG. 13 shows Embodiment 6 of the present invention.
It is an optical sectional view in the YZ plane. This embodiment is an imaging optical system of a zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0197]

[Outside 3]

[0198]

[Outside 4]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil, the second surface R2 to the fifth surface R5, and the sixth surface R6 to the ninth surface.
R9 is an integrated first and second optical element B1, B2, and a tenth surface R10 is an image surface.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1. In the first optical element B1, refraction occurs on the second surface R2, the third surface R3, the fourth surface R4.
And is refracted by the fifth surface R5, and exits the first optical element B1. At this time, a primary image is formed on an intermediate image forming surface near the fourth surface.

Next, the light beam enters the second optical element B2. In the second optical element B2, refraction occurs on the sixth surface R6, and the seventh surface R7 and the eighth surface R8
And is refracted by the ninth surface R9, and exits the second optical element B2. At this time, a pupil is formed near the seventh surface in the second optical element B2. The light beam emitted from the second optical element B2 finally forms an image on the tenth surface R10 (the imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and the same direction. In the second optical element B2, unlike the fifth embodiment, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and opposite to each other.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z plus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the image plane R10 is increased. In this embodiment, as compared with the fifth embodiment, the incident and emission reference axes of the second optical element B2 are in opposite directions. Therefore, when comparing the entire zoom range, the fifth embodiment is more compact than the fifth embodiment. I have.

FIGS. 14, 15 and 16 are lateral aberration diagrams of the present embodiment.

[Embodiment 7] FIG. 17 shows Embodiment 7 of the present invention.
It is an optical sectional view in the YZ plane. This embodiment is an imaging optical system of a zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0206]

[Outside 5]

[0207]

[Outside 6]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil, the second surface R2 to the fifth surface R5, and the sixth surface R6 to the ninth surface.
R9 is an integrated first and second optical element B1, B2, and a tenth surface R10 is an image surface.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1. In the first optical element B1, refraction occurs on the second surface R2, the third surface R3, the fourth surface R4.
And is refracted by the fifth surface R5, and exits the first optical element B1. At this time, the primary image is formed on the intermediate image forming surface near the fifth surface.

Next, the light beam enters the second optical element B2. In the second optical element B2, refraction occurs on the sixth surface R6, and the seventh surface R7 and the eighth surface R8
And is refracted by the ninth surface R9, and exits the second optical element B2. At this time, a pupil is formed near the seventh surface. Then, the luminous flux emitted from the second optical element B2 becomes the tenth surface R10 (CC
Finally, an image is formed on an imaging surface of an imaging medium such as D).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and opposite to each other. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and the same direction.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z minus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end,
The space between the second optical element B2 and the image plane R10 expands.

FIGS. 18, 19 and 20 are lateral aberration diagrams of the present embodiment.

[Embodiment 8] FIG. 21 shows an embodiment 8 of the present invention.
It is an optical sectional view in the YZ plane. This embodiment is an imaging optical system of a zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0215]

[Outside 7]

[0216]

[Outside 8]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil, the second surface R2 to the fifth surface R5, and the sixth surface R6 to the ninth surface.
R9 is an integrated first and second optical element B1, B2, and a tenth surface R10 is an image surface.

Hereinafter, the image forming operation when the object position is at infinity will be described. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1. In the first optical element B1, refraction occurs on the second surface R2, the third surface R3, the fourth surface R4.
And is refracted by the fifth surface R5, and exits the first optical element B1. At this time, a primary image is formed on an intermediate image forming surface near the fourth surface.

Next, the light beam enters the second optical element B2. In the second optical element B2, refraction occurs on the sixth surface R6, and the seventh surface R7 and the eighth surface R8
And is refracted by the ninth surface R9, and exits the second optical element B2. At this time, a pupil is formed near the seventh surface. Then, the luminous flux emitted from the second optical element B2 becomes the tenth surface R10 (CC
Finally, an image is formed on an imaging surface of an imaging medium such as D).

In this embodiment, in the first optical element B1, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and opposite to each other. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and opposite to each other.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z minus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z minus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the image plane R10 is increased.

FIGS. 22, 23 and 24 are lateral aberration diagrams of the present embodiment.

Embodiments 9 and 12 are two-group type zoom lenses as in Embodiments 5 to 8, but in the conventional ones, each optical element is provided with a curved reflecting surface on the surface of a block of transparent plastic, glass or the like. And the like, and the light rays from the object were transmitted repeatedly through this block. However, in Examples 9 to 12 below, the eccentric reflecting surfaces constituting each group are all surface mirrors made of plastics, glass, metal, etc.
Two surface mirrors constituting each group are connected and integrated outside the optical path.

[Embodiment 9] FIG. 25 shows Embodiment 9 of the present invention.
It is an optical sectional view in YZ. This embodiment is an imaging optical system of a two-unit zoom lens having a zoom ratio of about 1.5. The configuration data is described below.

[0225]

[Outside 9]

[0226]

[Outside 10]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil. The second surface R2 and the third surface R3, which are the reflecting surfaces, and the fourth surface R4 and the fifth surface R5 are connected together by connecting the side surfaces of the surface mirror to form first and second optical elements B1 and B2. doing. The sixth surface R6 is an image surface.

Hereinafter, the image forming operation when the object position is at infinity will be described. First, the light beam that has passed through the stop (entrance pupil), which is the first surface, enters the first optical element B1. Here, the light is reflected by the second surface R2 and the third surface R3, and exits the first optical element B1. At this time, a primary image is formed on an intermediate image forming surface near the third surface.

Next, the light beam enters the second optical element B2.
Here, the light is reflected by the fourth surface R4 and the fifth surface R5, and is reflected by the second optical element B2.
Exit the part. At this time, a pupil is formed near the fourth surface. The luminous flux exiting the second optical element B2 is the sixth surface
An image is finally formed on R6 (the imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and in the same direction. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and the same direction.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z plus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z minus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end,
The space between the second optical element B2 and the image plane R10 expands.

FIGS. 26, 27 and 28 are lateral aberration diagrams of this embodiment.

[Embodiment 10] FIG. 29 shows Embodiment 1 of the present invention.
FIG. 5 is an optical sectional view in the YZ plane of FIG. In this embodiment, the zoom ratio is approximately
1.5x two-unit zoom lens imaging optical system). The configuration data is described below.

[0234]

[Outside 11]

[0235]

[Outside 12]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil. The second surface R2 and the third surface R3, which are reflection surfaces, are connected to each other by connecting the side surfaces of the surface mirror to form a first optical element B1. In addition, the fourth surface R4 and the fifth surface
The surface R5 is formed on the integral second optical element B2. The sixth surface R6 is an image surface.

Hereinafter, the image forming operation when the object position is at infinity will be described. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1.
In the first optical element B1, the light is reflected by the second surface R2 and the third surface R3,
Exit the optical element B1. At this time, a primary image is formed on an intermediate image forming surface near the third surface.

Next, the light beam enters the second optical element B2.
In the second optical element B2, the light is reflected by the fourth surface R4 and the fifth surface R5,
Exit the optical element B2. At this time, a pupil is formed near the fourth surface. Then, the light flux that has exited the second optical element B2 finally forms an image on the sixth surface R6 (the imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and in the same direction. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and opposite to each other.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z plus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the image plane R10 is increased.

FIGS. 30, 31, and 32 are lateral aberration diagrams of the present embodiment.

[Embodiment 11] FIG. 33 shows Embodiment 1 of the present invention.
FIG. 1 is an optical sectional view in the YZ plane of FIG. In this embodiment, the zoom ratio is approximately
This is an imaging optical system of a 1.5x two-unit zoom lens. The configuration data is described below.

[0243]

[Outside 13]

[0244]

[Outside 14]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil. The second surface R2 and the third surface R3, which are reflection surfaces, are formed on the first optical element B1. The fourth which is a reflective surface
The surface R4 and the fifth surface R5 are connected to each other by connecting the side surfaces of the surface mirror to form a second optical element B2. 6th surface R6
Is the image plane.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1.
Here, the light is reflected by the second surface R2 and the third surface R3, and is reflected by the first optical element B1.
Exit the part. At this time, 1 is set on the intermediate imaging surface near the third surface.
The next image is formed.

Next, the light beam enters the second optical element B2.
Here, the light is reflected by the fourth surface R4 and the fifth surface R5, and is reflected by the second optical element B2.
Exit the part. At this time, a pupil is formed near the fourth surface. The luminous flux exiting the second optical element B2 is the sixth surface
An image is finally formed on R6 (an imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and opposite to each other. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and the same direction.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z minus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end,
The space between the second optical element B2 and the image plane R10 expands.

FIGS. 34, 35 and 36 are lateral aberration diagrams of the present embodiment.

[Embodiment 12] FIG. 37 shows Embodiment 1 of the present invention.
FIG. 2 is an optical cross-sectional view in the YZ plane of FIG. In this embodiment, the zoom ratio is approximately
This is an imaging optical system of a 1.5x two-unit zoom lens. The configuration data is described below.

[0252]

[Outside 15]

[0253]

[Outside 16]

In this embodiment, the first surface R1 is a stop surface which is an entrance pupil. The second surface R2 and the third surface R3, and the fourth surface R4 and the fifth surface R5 are surface mirrors formed on the first and second optical elements B1 and B2, respectively. The sixth surface R6 is an image surface.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1.
Here, the light is reflected by the second surface R2 and the third surface R3, and is reflected by the first optical element B1.
Exit the part. At this time, 1 is set on the intermediate imaging surface near the third surface.
The next image is formed.

Next, the light beam enters the second optical element B2.
Here, the light is reflected by the fourth surface R4 and the fifth surface R5, and is reflected by the second optical element B2.
Exit the part. At this time, a pupil is formed near the fourth surface. The luminous flux emitted from the second optical element B2 is applied to the sixth surface R6.
(Imaging surface of an imaging medium such as a CCD).

In this embodiment, in the first optical element B1, the direction of the incident reference axis and the direction of the emitting reference axis are parallel and opposite to each other. In the second optical element B2, the direction of the reference axis to be incident and the direction of the reference axis to be emitted are parallel and opposite to each other.

Next, a description will be given of the zooming effect due to the movement of each optical element. During zooming, the first optical element B1 moves in the Z minus direction from the wide-angle end to the telephoto end. The second optical element B2 moves in the Z minus direction from the wide angle end to the telephoto end. The tenth surface R10, which is the image surface, does not move during zooming. The distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the image plane R10 is increased.

FIGS. 38, 39 and 40 are lateral aberration diagrams of the present embodiment.

Embodiments 13 to 16 are so-called three-group zoom lenses.

[Embodiment 13] FIG. 41 shows Embodiment 13 of the present invention.
3 is an optical sectional view in the YZ plane. FIG. This embodiment is an imaging optical system of a three-unit zoom lens having a zoom ratio of about twice. Also, FIG.
2 is a perspective view of the present embodiment. The configuration data is described below.

[0262]

[Outside 17]

[0263]

[Outside 18]

[0264]

[Outside 19]

In FIG. 41, the first surface is a stop surface R1 as an entrance pupil, and the second surface R2 to the seventh surface R7, and the eighth surface R8 to the thirteenth surface.
The surface R13, the fourteenth surface R14 to the nineteenth surface R19 are respectively integrated first, second and third optical elements, and the twentieth surface R20 is an image surface.

Hereinafter, the image forming operation when the object position is set at infinity will be described. First, the light beam that has passed through the stop (entrance pupil) R1 enters the first optical element B1. First optical element
Within B1, refraction at the second surface R2, reflection at the third surface R3, fourth surface R4,
The light is totally reflected on the fifth surface R5, reflected on the sixth surface R6, refracted on the seventh surface R7, and exits the first optical element B1. Here, the second surface R2 and the fourth surface R4 are the same surface, and serve both as a refraction surface and a total reflection surface.
The same applies to the fifth surface R5 and the seventh surface R7. The luminous flux is on the fourth surface
An intermediate image is formed between R4 and the fifth surface R5.

Next, the light beam enters the second optical element B2.
In the second optical element B2, refraction occurs at the eighth surface R8, reflection occurs at the ninth surface R9, total reflection occurs at the tenth surface R10 and the eleventh surface R11, and twelfth surface R1 occurs.
2, the light is refracted by the thirteenth surface R13, and emerges from the second optical element B2. Here, the eighth surface R8 and the tenth surface R10 are the same surface, and serve both as a refraction surface and a total reflection surface. 11th surface R11 and 1st
The same applies to the three surfaces R13. The light beam forms an intermediate image near the twelfth surface.

Next, the light beam enters the third optical element B3.
In the third optical element B3, refraction occurs at the 14th surface R14, and the 15th surface
The light is reflected at R15, totally reflected at the sixteenth surface R16 and the seventeenth surface R17, reflected at the eighteenth surface R18, and refracted at the nineteenth surface R19, and exits the third optical element B3. Here, the 14th surface R14 and the 16th surface R16
Are the same surface and serve both as a refraction surface and a total reflection surface. Seventeenth
The same applies to the surface R17 and the nineteenth surface R19. The luminous flux is the first
An intermediate image is formed between the sixth surface R16 and the seventeenth surface R17.

Finally, the light beam emitted from the third optical element B3 forms an image on the twentieth surface R20 (the imaging surface of an imaging medium such as a CCD) of the final imaging surface.

Next, the movement of each optical element accompanying the magnification change operation will be described. During zooming, the first optical element B1 is fixed and does not move. The second optical element B2 moves back and forth along a locus convex in the Z plus direction from the wide-angle end to the telephoto end. The third optical element B3 moves in the negative Z direction from the wide-angle end to the telephoto end. The twentieth surface R20, which is the image surface, does not move during zooming.

When the magnification is changed from the wide-angle end to the telephoto end, the optical path length of the entire system from the first surface R1 to the image surface R20 is constant.

In this embodiment, the reference axes of incidence and emission of the three optical elements are parallel and in the same direction.

FIGS. 43, 44 and 45 are lateral aberration diagrams of the present embodiment. In this embodiment, as can be seen from the drawing, balanced aberration correction is obtained at each focal length.

In this embodiment, assuming that the image size is 8 × 6 mm, the length, width and thickness of the optical system are about 65.8 × 37 × 11.4 mm.
It has become about. As in the previous embodiments, since the thickness of the optical system is small and each reflecting surface can be configured as an optical element formed on the side surface of a plate-like block as shown in FIG. If one optical element is mounted and two of the optical elements are moved along the substrate surface, a thin zoom lens as a whole can be easily configured.

[Embodiment 14] FIG. 46 shows Embodiment 1 of the present invention.
4 is an optical cross-sectional view in the YZ plane. This embodiment is an imaging optical system of a three-unit zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0276]

[Outside 20]

[0277]

[Outside 21]

[0278]

[Outside 22]

In FIG. 46, the first surface is a stop surface R1 as an entrance pupil, and the second surface R2 to the seventh surface R7, the eighth surface R8 to the thirteenth surface.
The surface R13, the fourteenth surface R14 to the eighteenth surface R18 are respectively integrated first, second and third optical elements, and the nineteenth surface R19 is an image surface.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1 enters the first optical element B1. First optical element
Within B1, refraction at the second surface R2, reflection at the third surface R3, fourth surface R4,
The light is totally reflected on the fifth surface R5, reflected on the sixth surface R6, refracted on the seventh surface R7, and exits the first optical element B1. Here, the second surface R2 and the fourth surface R4 are the same surface, and serve both as a refraction surface and a total reflection surface.
The same applies to the fifth surface R5 and the seventh surface R7. The luminous flux is on the fourth surface
An intermediate image is formed between R4 and the fifth surface R5.

Next, the light beam enters the second optical element B2.
In the second optical element B2, refraction occurs at the eighth surface R8, reflection occurs at the ninth surface R9, total reflection occurs at the tenth surface R10 and the eleventh surface R11, and twelfth surface R1 occurs.
2, the light is refracted by the thirteenth surface R13, and emerges from the second optical element B2. Here, the eighth surface R8 and the tenth surface R10 are the same surface, and serve both as a refraction surface and a total reflection surface. 11th surface R11 and 1st
The same applies to the three surfaces R13. The light flux forms an intermediate image near the twelfth surface. Further, the light beam is transmitted from the second optical element B2 to the third optical element B2.
A pupil is formed with the optical element B3.

Next, the light beam enters the third optical element B3.
In the third optical element B3, refraction occurs at the 14th surface R14, and the 15th surface
The light is reflected at R15, totally reflected at the sixteenth surface R16, reflected at the seventeenth surface R17, and refracted at the eighteenth surface R18, and exits the third optical element B3. Here, the fourteenth surface R14, the sixteenth surface R16, and the eighteenth surface R18 are the same surface and serve both as a refraction surface and a total reflection surface.

[0283] Finally, the light beam emitted from the third optical element B3 forms an image on the final imaging surface 19th surface R19 (the imaging surface of an imaging medium such as a CCD).

Next, the movement of each optical element accompanying the zooming operation will be described. During zooming, the first optical element B1 is fixed and does not move. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. Third optical element B3
Moves in the Z plus direction from the wide-angle end to the telephoto end.
The nineteenth surface, which is the image surface, does not move during zooming.

Here, the distance between the first optical element B1 and the second optical element B2 is widened by zooming from the wide-angle end to the telephoto end, and the second optical element B2 and the third optical element B3 Is narrowed, and the space between the third optical element B3 and the image plane R19 is widened. Also, from the first surface R1 to the image surface from the wide-angle end to the telephoto end,
The optical path length of the entire system between R19 changes to be longer.

In this embodiment, the reference axes of incidence and emission of the first optical element B1 are parallel and opposite to each other, and the reference axes of incidence and emission of the second and third optical elements B2 and B3 are both parallel. In the same direction.

FIGS. 47, 48 and 49 are lateral aberration diagrams of this embodiment.

[Embodiment 15] FIG. 50 shows Embodiment 1 of the present invention.
FIG. 5 is an optical sectional view in the YZ plane of FIG. This embodiment is an imaging optical system of a three-unit zoom lens having a zoom ratio of about twice. The configuration data is described below.

[0289]

[Outside 23]

[0290]

[Outside 24]

[0291]

[Outside 25]

In FIG. 50, a first surface R1 is a stop surface serving as an entrance pupil, a second surface R2 to a sixth surface R6, a seventh surface R7 to an eleventh surface R11.
The twelfth surface R12 to the sixteenth surface R16 are the first, second and third optical elements, respectively, and the seventeenth surface R17 is the image surface.

The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1, which is the first surface, enters the first optical element B1.
In the first optical element B1, the first optical element is refracted on the second surface R2, reflected on the third surface R3, totally reflected on the fourth surface R4, reflected on the fifth surface R5, and refracted on the sixth surface R6. Inject B1. Here, the second surface R2,
The fourth surface R4 and the sixth surface R6 are the same surface, and serve both as a refraction surface and a total reflection surface. Further, the first optical element B1 has an intermediate image plane near the fifth surface R5.

Next, the light beam emitted from the first optical element B1 enters the second optical element B2. In the second optical element B2, the light is refracted on the seventh surface R7, reflected on the eighth surface R8, totally reflected on the ninth surface R9, reflected on the tenth surface R10, and refracted on the eleventh surface R11. Inject B2. Here, the seventh surface R7, the ninth surface R9, the eleventh surface
The surface R11 is the same surface and serves as both a refraction surface and a total reflection surface.

Next, the light beam emitted from the second optical element B2 enters the third optical element B3. In the third optical element B3, refraction occurs at the twelfth surface R12, reflection occurs at the thirteenth surface R13, and fourteenth surface R14.
, Is reflected at the fifteenth surface R15, refracted at the sixteenth surface R16, and exits the third optical element B3. Here, the twelfth surface R12
, The fourteenth surface R14 and the sixteenth surface R16 are the same surface and serve as both a refracting surface and a total reflection surface.

Finally, the light beam emitted from the third optical element B3 forms an image on the 17th surface R17 (imaging surface of an imaging medium such as a CCD) on the final imaging surface.

Next, the movement of each optical element accompanying the zooming operation will be described. During zooming, the first optical element B1 is fixed and does not move. The second optical element B2 moves in the Z plus direction from the wide angle end to the telephoto end. Third optical element
B3 also moves in the Z plus direction from the wide-angle end to the telephoto end. The seventeenth surface, which is the image surface, does not move during zooming.

Here, the distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the distance between the second optical element B2 and the third optical element B3 is reduced. The distance is reduced, and the distance between the third optical element B3 and the image plane is increased. Also,
The optical path length of the entire system from the first surface R1 to the image surface R17 changes from the wide angle end to the telephoto end so as to be shorter.

In this embodiment, the reference axes of incidence and emission of the three optical elements are parallel and opposite to each other.

FIGS. 51, 52 and 53 are lateral aberration diagrams of the present embodiment.

[Embodiment 16] FIG. 54 shows Embodiment 1 of the present invention.
6 is an optical sectional view in the YZ plane of FIG. In this embodiment, the zoom ratio is approximately
This is an image pickup optical system of a 2.9x three-group zoom lens. The configuration data is described below.

[0302]

[Outside 26]

[0303]

[Outside 27]

[0304]

[Outside 28]

[0305]

[Outside 29]

In FIG. 54, the first surface is a stop surface R1 as an entrance pupil, and the second surface R2 to the eighth surface R8, and the ninth surface R9 to the fifteenth surface.
The surface R15, the sixteenth surface R16 to the twenty-second surface R22 are respectively integrated first, second and third optical elements, and the twenty-third surface R23 is an image surface.

[0307] The image forming operation when the object position is at infinity will be described below. First, the light beam that has passed through the stop (entrance pupil) R1 enters the first optical element B1. First optical element
Within B1, the second surface R2 is refracted, the third surface R3, the fourth surface R4, the fifth surface
The light is reflected by R5, the sixth surface R6, and the seventh surface R7, refracted by the eighth surface R8, and emerges from the first optical element B1. Here, the light beam forms an intermediate image near the fourth surface R4. Further, a secondary image is formed between the first optical element B1 and the second optical element B2.

Next, the light beam enters the second optical element B2.
In the second optical element B2, the ninth surface R9 is refracted, and the eleventh surface R11
The light is reflected by the twelfth surface R12, the thirteenth surface R13, and the fourteenth surface R14, refracted by the fifteenth surface R15, and emerges from the second optical element B2. Here, the light beam has an intermediate image plane between the twelfth surface R12 and the thirteenth surface R13. Further, the light beam forms a pupil near the fifteenth surface R15.

Next, the light beam emitted from the second optical element B2 enters the third optical element B3. In the third optical element B3, refraction occurs on the sixteenth surface R16, and the seventeenth surface R17, the eighteenth surface R18, the first
Reflected by the ninth surface R19, the twentieth surface R20, and the twenty-first surface R21, the twentieth surface
The light is refracted by the surface R22 and exits the third optical element B3. Here, the light beam forms an intermediate image near the eighteenth surface R18.

Finally, the light beam emitted from the third optical element B3 forms an image on the 23rd surface R23 (the image pickup surface of an image pickup medium such as a CCD) which is the final image formation surface.

Next, the movement of each optical element accompanying the zooming operation will be described. During zooming, the first optical element B1 is fixed and does not move. The second optical element B2 moves in the Z minus direction from the wide angle end to the telephoto end. Third optical element
B3 moves in the Z minus direction from the wide-angle end to the telephoto end. The twentieth surface R20, which is the image surface, does not move during zooming.

Here, the distance between the first optical element B1 and the second optical element B2 is reduced by zooming from the wide-angle end to the telephoto end, and the second optical element B2 and the third optical element B3 Is widened, and the space between the third optical element B3 and the image plane R23 is widened. Also, from the first surface R1 to the image surface from the wide-angle end to the telephoto end,
The optical path length of the entire system between R23 is changing to be longer.

In this embodiment, the reference axes of incidence and emission of the three optical elements are parallel and opposite to each other.

FIGS. 55, 56 and 57 are lateral aberration diagrams of the present embodiment.

In the present invention, an optical element in which two refracting surfaces and a plurality of reflecting surfaces are formed on the surface of the transparent body constituting Examples 5 to 8 and Examples 13 to 16;
The zooming is performed by using a plurality of optical elements integrally formed with a plurality of reflecting surfaces composed of surface reflecting mirrors constituting the mirror 12 and changing the relative positions of at least two of the optical elements. A reflective zoom optical system can also be configured. Also in this case, effects such as gradual arrangement accuracy (assembly accuracy) of the reflection mirror can be obtained.

Of the above embodiments, the first to eighth and thirteenth to sixteenth embodiments each have an optical system in which two refracting surfaces and a plurality of reflecting surfaces such as curved surfaces and flat surfaces are formed on side surfaces of a thin plate-like block. The zooming is performed by moving two optical elements relative to the image plane.

In all the embodiments, the curved reflecting surfaces formed on the optical element are all decentered curved reflecting surfaces, and they are all decentered in one plane (YZ). Then, the magnification is changed by moving the two optical elements in one direction in parallel with the YZ plane.

According to the present invention, the optical system can be constituted by a thin optical element, and a structure that moves on one plane can be adopted as a zoom structure, so that a thin zoom lens can be easily constituted.

Further, since the direction of the reference axis emitted from each optical element can be easily set in the same direction as the direction of the incident reference axis or in the opposite direction, the degree of freedom in setting the overall shape of the optical system is increased. Extremely large, thus giving the camera configuration great freedom.

In each case, a well-balanced aberration correction is obtained at each focal length.

Further, according to the present invention, the embodiment 13
By setting the incident reference axis of the fixed optical element (first optical element B1) at the time of zooming at an arbitrary angle with respect to the moving plane of the optical element that moves at the time of zooming, as in the case of a camera such as 16 The degree of freedom can be further increased.

FIG. 58 shows a second optical element (first optical element B1) that does not move at the time of zooming.
FIG. 11 is a perspective view of an optical system tilted at an arbitrary angle with respect to a moving plane of a third optical element. In the figure, B1 is a first optical element that does not move at the time of zooming, and corresponds to a so-called front lens of a photographing optical system. B2 and B3 are second and third optical elements that move during zooming, respectively. The second optical element B2 corresponds to a so-called variator, and the third optical element B3 corresponds to a compensator.

The second and third optical elements B2 and B3 are shown in FIG.
8 on the YZ plane to change the magnification. In addition, all reference axes in the second and third optical elements B2 and B3 exist on the YZ plane.

The second and third optical elements B which move during zooming
2, B3 cannot tilt the plane including the YZ plane and the reference axis for the above reason. However, the first fixed
In the optical element B1, the part of the reference axis (A _{1,2 to} A ₁ , ₆ ) must exist in the reference axis plane, but the other part of the reference axis (A ₀ , A ₁₎ , ₁ ) is the reference axis plane (moving plane)
It does not need to be inside.

[0325] That is, in this embodiment, Z-axis by the surface R _{1, 2} in the direction of the reference axis A ₀ which enters the reflective surface R _{1, 2} from the X-axis direction is provided within the first optical element B1 Is deflected in the direction.

By providing the reflecting surfaces R ₁ and R ₂ as described above, the direction of the light beam incident on the photographing optical system can be freely set, and the degree of freedom in the form of the camera can be further increased.

In the above embodiments, the first surface is used as the stop. However, depending on the configuration of the optical system, the stop may be provided between the optical elements. However, in that case, the entrance pupil formed by the optical element on the object side of the stop is formed closer to the object side than the first reflection surface, counting from the object side of the optical element on which the light beam from the object first enters. If the stop is set on the first surface, it is almost equivalent to that of the first embodiment, so that the same effect as that of the above-described embodiment can be obtained.

[0328]

According to the present invention, by setting each element as described above, the size of the entire mirror optical system can be reduced, and the arrangement accuracy (assembly accuracy) of the reflection mirror, which is often present in the mirror optical system, can be reduced. It is an object of the present invention to provide an optical system capable of performing such an operation and an imaging apparatus using the same.

Further, by arranging the stop closest to the object side and forming an object image at least once in the optical system, the effective diameter of the optical system can be reduced.
By giving appropriate refractive power to the plurality of reflecting surfaces constituting the optical element and eccentrically arranging the reflecting surfaces constituting each optical element, the optical path is bent into a desired shape and the total length in a predetermined direction is reduced. And an image pickup apparatus using the same.

In addition, according to the present invention, (A-1) In an optical system having a plurality of optical elements integrally formed with a plurality of reflecting surfaces having a curvature, the relative positions of the plurality of optical elements are changed. By adopting a configuration in which zooming and focusing of the optical system are performed, the reflecting surface that moves at the time of zooming is unitized. Since the relative positional accuracy of each reflecting surface requiring accuracy can be guaranteed, deterioration of optical performance due to zooming can be prevented. (A-2) Since the optical element itself functions as a lens barrel because an optical element having a reflecting surface formed integrally is used,
A mount member that is significantly simpler than a conventional lens barrel can be used. (A-3) Since each optical element is a lens unit in which a plurality of surfaces having a curvature are integrally formed as compared with a refracting lens system, the number of parts in the entire photographing system can be reduced. Therefore, cost reduction of the imaging system can be achieved in terms of the number of parts.

Further, since the number of parts in the entire photographing system can be reduced, the accumulated error due to the mounting of the parts can be reduced, and the deterioration of the optical performance can be prevented. (A-4) By eccentrically arranging each reflection surface on the optical element at an appropriate position, the optical path in the optical system can be bent into a desired shape, and shortening of the optical system in the entire length direction can be achieved. (A-5) By providing a fixed optical element at the time of zooming, a part of the reference axis can be inclined at an arbitrary angle with respect to a plane including most of the reference axis, and the degree of freedom in the form of the camera can be increased. I can do it. (A-6) By adopting a configuration in which an object image is transmitted by repeating image formation a number of times, the effective beam diameter of each surface is suppressed small, and the entire photographing optical system is made compact. (A-7) By setting the image formation size of the intermediate image formation surface to be relatively small as compared with the image pickup device surface size, it is possible to suppress the effective beam diameter of each surface when transmitting an object image. (A-8) By setting a plane on which the optical element moves in parallel with a plane including most of the reference axes, including a reference axis in the two optical elements that change the relative position, the optical element can be used when zooming. Even if it moves, the parallelism between the plane including the reference axis and the plane on which each optical element moves can be easily maintained. Therefore, the occurrence of eccentric aberration caused by the inclination between the moving plane of the optical element that moves during zooming and the plane including the reference axis is eliminated. (A-9) Since the movement of each optical element during zooming is performed on one plane, parallel eccentricity in the direction perpendicular to the moving direction can be easily prevented. Further, rotation in a plane perpendicular to the moving plane can be removed in principle. (A-10) Since each optical element is arranged on one plane, each optical element can be incorporated from one direction,
Assembly is facilitated, and assembly costs can be reduced. (A-11) The stop arranged in the optical system is arranged on the object side of the optical system, or the entrance pupil is counted from the object side of the optical element where the light flux from the object first enters from the first reflection surface to the object. By forming the zoom lens on the side, it is possible to achieve a zoom lens in which the lens diameter does not increase even when the angle of view of the optical system is widened. Thus, it is possible to achieve an optical system having at least one effect and an imaging device using the same.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a coordinate system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part of a first embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a scaling operation according to the first embodiment;

FIG. 4 is a schematic diagram of a main part of a second embodiment of the present invention.

FIG. 5 is a schematic view of a main part of a third embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining a scaling operation according to a third embodiment.

FIG. 7 is a schematic diagram of a main part of a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining a scaling operation according to a fourth embodiment.

FIG. 9 is an optical sectional view in the YZ plane according to a fifth embodiment of the present invention.

FIG. 10 is a lateral aberration diagram of the fifth embodiment (at the wide-angle end).

FIG. 11 is a lateral aberration diagram of Example 5 (intermediate position).

FIG. 12 is a lateral aberration diagram of the fifth embodiment (telephoto end).

FIG. 13 is an optical sectional view in the YZ plane according to a sixth embodiment of the present invention.

FIG. 14 is a lateral aberration diagram of the sixth embodiment (at the wide-angle end).

FIG. 15 is a lateral aberration diagram of Example 6 (intermediate position).

FIG. 16 is a lateral aberration diagram of the sixth embodiment (telephoto end).

FIG. 17 is an optical sectional view in the YZ plane according to a seventh embodiment of the present invention.

FIG. 18 is a lateral aberration diagram of the seventh embodiment (at the wide-angle end).

FIG. 19 is a lateral aberration diagram of Example 7 (intermediate position).

FIG. 20 is a lateral aberration diagram of the seventh embodiment (telephoto end).

FIG. 21 is an optical sectional view in the YZ plane of Embodiment 8 of the present invention.

FIG. 22 is a lateral aberration diagram of the eighth embodiment (at the wide-angle end).

FIG. 23 is a lateral aberration diagram of Example 8 (intermediate position).

FIG. 24 is a lateral aberration diagram of the eighth embodiment (telephoto end).

FIG. 25 is an optical sectional view in the YZ plane of a ninth embodiment of the present invention.

FIG. 26 is a lateral aberration diagram of the ninth embodiment (at the wide-angle end).

FIG. 27 is a lateral aberration diagram of the ninth embodiment (intermediate position).

FIG. 28 is a lateral aberration diagram of the ninth embodiment (telephoto end).

FIG. 29 is an optical cross-sectional view in the YZ plane of Embodiment 10 of the present invention.

FIG. 30 is a lateral aberration diagram of the tenth embodiment (at the wide-angle end).

FIG. 31 is a lateral aberration diagram of the tenth embodiment (intermediate position).

FIG. 32 is a lateral aberration diagram of the tenth embodiment (telephoto end).

FIG. 33 is an optical sectional view in the YZ plane of an eleventh embodiment of the present invention.

FIG. 34 is a lateral aberration diagram of the eleventh embodiment (at the wide-angle end).

FIG. 35 is a lateral aberration diagram of the eleventh embodiment (intermediate position).

FIG. 36 is a lateral aberration diagram of the eleventh embodiment (telephoto end)

FIG. 37 is an optical sectional view in the YZ plane of a twelfth embodiment of the present invention.

FIG. 38 is a lateral aberration diagram of the twelfth embodiment (wide angle end).

FIG. 39 is a lateral aberration diagram of the twelfth embodiment (intermediate position).

FIG. 40 is a lateral aberration diagram of the twelfth embodiment (telephoto end).

FIG. 41 is an optical sectional view in the YZ plane of a thirteenth embodiment of the present invention.

FIG. 42 is a perspective view of a thirteenth embodiment.

FIG. 43 is a lateral aberration diagram of the thirteenth embodiment (at the wide-angle end).

FIG. 44 is a lateral aberration diagram of the thirteenth embodiment (intermediate position).

FIG. 45 is a lateral aberration diagram of the thirteenth embodiment (telephoto end).

FIG. 46 is an optical sectional view in the YZ plane of a fourteenth embodiment of the present invention.

FIG. 47 is a lateral aberration diagram of Example 14 (at the wide-angle end).

FIG. 48 is a lateral aberration diagram of the fourteenth embodiment (intermediate position).

FIG. 49 is a lateral aberration diagram of the fourteenth embodiment (telephoto end).

FIG. 50 is an optical sectional view in the YZ plane of Embodiment 15 of the present invention.

FIG. 51 is a lateral aberration diagram of Example 15 (at the wide-angle end).

FIG. 52 is a lateral aberration diagram of Example 15 (intermediate position).

FIG. 53 is a diagram showing the lateral aberration of the fifteenth embodiment (telephoto end)

FIG. 54 is an optical sectional view in the YZ plane of a sixteenth embodiment of the present invention.

FIG. 55 is a lateral aberration diagram of Example 16 (at the wide-angle end).

FIG. 56 is a lateral aberration diagram of the sixteenth embodiment (intermediate position).

FIG. 57 is a lateral aberration diagram of the sixteenth embodiment (telephoto end).

FIG. 58 shows that the incident reference axis is YZ in the three-unit zoom lens.
Perspective view of an optical system tilted at an arbitrary angle to a plane

FIG. 59 is a basic configuration diagram of a Cassegrain-type reflection telescope.

FIG. 60 is an explanatory view of a first method of separating a principal ray from an optical axis and preventing vignetting in a mirror optical system.

FIG. 61 is an explanatory view of a second method for separating a principal ray from an optical axis and preventing vignetting in a mirror optical system.

FIG. 62 is a schematic view of a conventional zoom optical system using a reflection mirror.

FIG. 63 is a schematic view of an observation optical system having a curvature on a prism reflecting surface.

FIG. 64 is a schematic view of an observation optical system having a curvature on another prism reflection surface.

[Explanation of symbols]

Ri, R _{m, n} surface Bi i-th optical element Di surface spacing along reference axis Ndi Refractive index νdi Abbe number A _{i, j} reference axis B _L = R1 Aperture P Final image plane Ni Intermediate imaging

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Norihiro Namba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Hiroshi Saruwatari 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kenshi Akiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (10)

[Claims] 1. An optical element having a curved reflecting surface inclined with respect to a reference axis, wherein the curved reflecting surface is an aspheric surface having no two or more symmetrical surfaces defining a pair of symmetrical surfaces, An optical system, wherein an entrance pupil is provided on the object side of the curved reflecting surface of the optical element. 2. An optical element having a curved reflecting surface inclined with respect to a reference axis, wherein the curved reflecting surface is an aspherical surface having only one symmetric surface defining a pair of symmetric surfaces. An optical system having an entrance pupil provided on the object side of an optical element. 3. A curved reflecting surface inclined with respect to a reference axis, wherein A = (a + b) · (y ² · cos ² t + x ² ) B = 2a · b・ Cos t [1 + {(ba) ・ y ・ sin t / (2a ・ b)} + [1 + {(ba)
・ Y ・ sin t / (a ・ b)}-{y ² / (a ・ b)}-{4a ・ b ・ cos ² t + (a + b) ² sin
² t} x ² / (4a ² b ² cos ² t)) ^1/2 ] as z = A / B + C ₀₂ y ² + C ₂₀ x ² + C ₀₃ y ³ + C ₂₁ x ² y + C ₀₄ y ⁴ + C ₂₂ x ² y ² + C ₄₀
includes an optical element in which is defined by x ^4, an optical system characterized by comprising an entrance pupil on the object side of said curved reflecting surfaces of the optical element. 4. The optical system according to claim 1, wherein the optical system has a plurality of curved surfaces, and the plurality of curved surfaces sequentially deflect a light beam. 5. The optical system according to claim 1, further comprising a curved refracting surface. 6. The optical system according to claim 5, wherein the reflection surface is provided on a surface of a surface reflection mirror. 7. The optical system according to claim 5, wherein the reflection surface is provided on a surface of a transparent body. 8. The optical system according to claim 1, wherein a stop is provided on the object side of said optical element. 9. An imaging apparatus comprising the optical system according to claim 1. Description: 10. An image forming apparatus comprising the optical system according to claim 1. Description: